This article was originally published on the Arnold Arboretum's website, and has been republished here with permission from the Arnold Arboretum. Picking the right plant for the right spot requires getting into the “zone.” Professional horticulturists, nursery operators, and home gardeners alike rely on plant hardiness zone maps to help them choose plants with the best chance of survival in their regions. Over the past century, the Arnold Arboretum and the United States Department of Agriculture (USDA) in particular have produced maps charting estimations of plant hardiness which have been periodically revised to reflect on-going changes in environments due to global warming and climate change. The story of hardiness zones begins at the Arnold Arboretum. In 1927, Arboretum taxonomist Alfred Rehder published the Manual of Cultivated Trees and Shrubs Hardy in North America.